1824.] Geological Society. 465 



Fellow, and a paper was read, On three Species of Birds, one 

 hitherto undescribed, and the others new to the Ornithology, of 

 the British Islands ; by N. A. Vigors, Jun., Esq. FLS. We shall 

 present a report of this paper in our next. 



GEOLOGICAL SOCIETY. 



Nov. 5. — A paper was read entitled " Observations on a 

 Comparison between the Beds below the Chalk in the Isle of 

 Wight, and in the Counties of Surrey, Kent, and Sussex ; " by 

 Thomas Webster, Esq. Sec. G. S. 



Mr. Webster stated, that in a late visit to the Isle of Wight, 

 he had been so fortunate as to discover a rock of the same 

 nature as the calciferous sandstone of Hastings, a circumstance 

 that has furnished him with a fixed point, by means of which he 

 had been enabled to compare the beds in the Isle of Wight with 

 those of the south-east part of England more correctly than had 

 been done before ; and he presented a table of what he consi- 

 dered as the equivalent beds in these two places. He imagined 

 that these equivalents had been hitherto stated erroneously by 

 several geologists ; and he attributed this chiefly to the follow- 

 ing causes : — 1st, The imperfect state of the science of geognosy 

 which had not as yet established fixed principles of classifica- 

 tion : 2dly, The want of acknowledged types of beds or forma- 

 tions, to which all other parts might be referred : 3dly, The 

 difficulties attending; actual examinations, arising from the defi- 

 ciencies or want of continuity of some beds, and the variation in 

 the composition and structure of others; difficulties which had, 

 in his opinion, been underrated. 



The author then proceeded to point out in detail what he 

 conceived to be the history of some of the errors that had been 

 fallen into. Thus, until lately, the descriptions given by various 

 geologists of the rock called green sand were supposed to be 

 applied to one bed only, whereas, in fact, there are two beds dis- 

 tinct from each other, the underclift' of the Isle of Wight, and 

 the rock of Folkstone, each of which had received this denomi- 

 nation. Also in the groups which it had been found necessary 

 to form, they had not agreed with each other as to the indivi- 

 dual beds enclosed in one group. Thus, some had formed a 

 group (which they called the ferruginous sand) of the sands 

 above and below the weald clay ; while others had attached the 

 name of ferruginous sand to those below the weald clay otilu. 

 He had also reason to fear, that an error had been committed 

 in not identifying the beds which are called the ferruginous sand, 

 on the west of the chalk, as the Carstone, Wobourn sand, and 

 the Faringdon bed, with the beds in the wealds of Kent and 

 Sussex to which the name oi green sand had been given. 



New Series, VOL. VIII. 2h 



